Slow release brown coal-urea fertiliser for improving crop yield, nitrogen use efficiency and soil health

Synthetic nitrogen (N) fertilisers, such as urea, are susceptible to rapid dissipation from soil. More gradual release of mineral N from fertiliser may reduce the off-site movement of mineral N, thereby enhancing N supply to crops and minimising negative off-site impacts. In this thesis, novel slow release fertilisers were formed by blending brown coal (BC) with urea which delayed fertiliser N release through strong retention facilitated by the extensive surface area, porous structure and chemical functional groups in the BC. Granulation of urea with BC substantially increased fertiliser-N availability to crop plants by decreasing gaseous and leaching losses which facilitated better crop growth and increased biomass and economic yield.